docs: def pdf_Gates_Gaudin_Schuhman_basis_integral(d, d_characteristic, m, n):
      r'''Calculates the integral of the multiplication of d^n by the Gates, 
      Gaudin and Schuhman (GGS) model given a particle diameter `d`,
      characteristic (maximum) particle diameter `d_characteristic`, and exponent
      `m`.
      
      .. math::
          \int d^n\cdot q(d)\; dd =\frac{m}{m+n} d^n \left(\frac{d}
          {d_{characteristic}}\right)^m
          
      Parameters
      ----------
      d : float
          Specified particle diameter, [m]
      d_characteristic : float
          Characteristic particle diameter; in this model, it is the largest 
          particle size diameter in the distribution, [m]
      m : float
          Particle size distribution exponent, [-]    
      n : int
          Exponent of the multiplied n, [-]
  
      Returns
      -------
      pdf_basis_integral : float
          Integral of Rosin Rammler pdf multiplied by d^n, [-]
  
      Notes
      -----
      This integral does not have any numerical issues as `d` approaches 0.
  
      Examples
      --------
      >>> pdf_Gates_Gaudin_Schuhman_basis_integral(d=2E-4, d_characteristic=1E-3, m=2.3, n=-3)
      -10136984887.543015
      '''
      return m/(m+n)*d**n*(d/d_characteristic)**m